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Thomas Edison: Telephone, Electricity and Phonograph, 1915

Phonograph

Edison always worked overlapping projects and such was the case with the phonograph. His first ideas came at the same time that he was working on the telephone transmitter and was related to his first inventions where the aim was to obtain a permanent copy of messages sent by telegraph. Now he wondered at ways of creating a permanent copy of messages sent by telephone. In fact, his February 19, 1878 patent refers to the "Phonograph or Speaking Machine."

The original tinfoil phonograph had three components:

  1. the speaker tube containing a diaphragm attached to a scribing stylus,
  2. a four-inch diameter metal drum attached to a hand crank and wrapped around with a roll of tinfoil, and
  3. the listening tube, very similar to the speaking tube, containing a detecting stylus attached to a diaphragm.

In operation, spoken sound entered the speaking tube, causing the diaphragm to vibrate. The vibrations passed through the stylus and were inscribed on the tinfoil in a vertical groove (hill and dale) pattern while the drum was being rotated by hand at 60 revolutions per minute. When the stylus of the listening tube rode over the recorded indentations, the resulting vibrations passed through the detecting stylus and vibrated the listening diaphragm to reproduce the speech in the listening tube. The cylinder had a three-minute recording capacity. On this completely original machine Edison made the first recording of human voice as he recited "Mary Had A Little Lamb." Public demonstrations cemented Edison's reputation as an outstanding inventor.

For commercial applications, the tinfoil material proved too flimsy and Edison switched his attention to his light bulb experiments. Meanwhile, other inventors such as Alexander Graham Bell and Charles Sumner Tainter worked on improving Edison's invention. The result was a change from tinfoil to wax cylinders with a floating, less destructive stylus. Now Edison turned his attention back to the phonograph; the Menlo Park laboratory went to work and produced an improved wax cylinder machine in 1889.

A novel and expensive feature of this machine was the electric motor included to drive the drum. The expense limited its market to office-dictating machine uses and Edison moved on again to other research. He later had some success with reproducing phonograph recordings and in a dictating phonograph, the Ediphone.

By the time another ten years had passed, the phonograph industry had turned to longer playing, more durable discs rather than cylinders as a recording medium, and music was now the recording content. While Edison adapted to this with new materials to improve disc recording and copying fidelity and a spring drive motor his product was incompatible with other systems and his endeavors were overtaken by companies such as the Victor Talking Machine Company and Columbia.